Effect of electroacupuncture on ventricular structure and function in rats with myocardial ischemia-reperfusion injury.

Objectives: To observe the effect of electroacupuncture (EA) on changes of ventricular structure and function in rats with myocardial ischemia-reperfusion injury (MIRI), so as to explore its potential mechanisms underlying improvement of ventricular remodeling after MIRI.

Methods: Forty male SD rats were randomly divided into 4 groups：sham operation group, model group, EA group and medication (sacubactril valsartan, LCZ696) group, with 10 rats in each group. The MIRI model was established by ligation of the left anterior descending coronary artery and reperfusion. EA (2 Hz/100 Hz, 2 mA) was applied to bilateral "Neiguan" (PC6) for 20 min, once every other day for 21 d. Rats of the medication group received gavage of LCZ696 (60 mg·kg·d). After the intervention, echocardiography was used to detect the ejection fraction (EF) and fractional shortening (FS) of the left ventricle, and the contents of serum tumor necrosis factor-α(TNF-α), vascular cell adhesion molecule-1(VCAM-1) and intercellular cell adhesion molecule-1(ICAM-1) were assayed by enzyme-linked immunosorbent assay. The pathological changes of myocardial tissue were observed after HE staining. The Masson staining was used to evaluate the myocardial collagen deposition and myocardial fibrosis. The mRNA expression levels of collagen Ⅰ and Ⅲ and connective tissue growth factor (CTGF) in the myocardial tissue were detected by quantitative real-time PCR, and the expression levels of IL-1β and IL-18 were detected by Western blot.

Results: In contrast to the sham operation group, the EF and FS levels of the left ventricle were ob-viously decreased (<0.001), while the contents of serum TNF-α, VCAM-1 and ICAM-1, the proportion of myocardial fibrosis area, the mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF, the expression levels of IL-1β and IL-18 were significantly increased (<0.001, <0.000 1, <0.05, <0.01) in the model group. Compared with the model group, the EF and FS levels were remarkably increased (<0.01), whereas the contents of serum TNF-α, VCAM-1 and ICAM-1, the proportion of myocardial fibrosis area, the mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF, and the expression levels of IL-1β and IL-18 were significantly down-regulated (<0.001, <0.01, <0.05) in both the medication and EA groups. No significant differences were found between the EA and medication groups in all the indexes mentioned above.

Conclusions: EA can improve the left-ventricular fibrosis and function, delay or reverse ventricular remodeling in MIRI rats, which may be related to its functions in down-regulating myocardial inflammatory response and mRNA expression levels of myocardial collagen Ⅰ, collagen Ⅲ and CTGF.